A single phase permanent magnet motor usually consists of a stator core, stator windings, and a permanent magnet rotor. The stator core is generally U-shaped, including two spaced pole arms. A pole claw is formed at a distal end of each pole arm. An inner wall surface of each pole claw is inwardly recessed to form an arc pole surface. The windings are wound around the pole arms. The rotor is disposed between the two pole claws and confronts the arc pole surface. In this type of motor, the pole arms of the stator core are separated apart, with large openings formed between the two pole claws. The openings lead to a large cogging torque formed between the stator and the rotor, thus making the motor operation unstable and causing noise.